Determination of the size of the pelvis. External conjugate: special obstetric examination

4 sizes of the large pelvis are determined.

Distantia spinarum - the distance between the anterior-superior spines of the iliac bones is 25-26 cm.
Distantia cristarum - the distance between the distant points of the iliac crests is 28-29 cm.
Distantia trochanterica - the distance between the large trochanters of the femur, normally 30-31 cm.
Conjugata externa (external conjugate, straight size of the pelvis) - the distance from the middle of the upper-outer edge of the symphysis to the supra-sacral fossa, located between the spinous process of the V lumbar vertebra and the beginning of the middle sacral ridge (coincides with the upper angle of the Michaelis rhombus), is 20-21 cm.

The size of the small pelvis

1. The plane of the entrance to the pelvis is limited by the upper edge of the symphysis, the upper-inner edge of the pubic bones (in front), the arcuate lines of the ilium (from the sides), the sacral promontory (in the back). This border between the large and small pelvis is called the border (nameless) line.

Conjugata vera (true conjugate, direct size of the entrance to the small pelvis) - the distance from the inner surface of the symphysis to the promontory of the sacrum; to determine the true conjugate, 9 cm is subtracted from the dimensions of the external conjugate.Normally, the true conjugate is 11 cm.
Anatomical conjugate - the distance from the cape to the middle of the upper inner edge of the symphysis (11.5 cm).
Transverse dimension - the distance between the most distant points of the arched lines (13-13.5 cm).
The oblique dimensions are 12-12.5 cm. The right oblique dimension is the distance from the right sacroiliac junction to the left ilio-pubic eminence (eminentia iliopubica). Left oblique dimension - the distance from the left sacroiliac junction to the right ilio-pubic eminence (eminentia iliopubica).

2. The plane of the wide part of the pelvic cavity is limited by the middle of the inner surface of the symphysis (in front), the middle of the acetabulum (from the sides) and the junction of the II and III sacral vertebrae (behind).

Direct size - the distance from the junction of the II and III sacral vertebrae to the middle of the inner surface of the symphysis, is 12.5 cm.
Transverse dimension is the distance between the midpoints of the acetabulum (12.5 cm).

3. The plane of the narrow part of the pelvic cavity is limited by the lower edge of the symphysis (in front), the spines of the ischial bones (from the sides) and the sacrococcygeal junction (behind),

Straight size - the distance from the sacrococcygeal junction to the lower edge of the symphysis (11-11.5 cm).
Transverse dimension - the distance between the spines of the ischial bones (10.5 cm).

4. The plane of the exit of the pelvis is limited by the lower edge of the symphysis (front), ischial tubercles (from the sides) and the apex of the coccyx (back).

Straight size - from the top of the coccyx to the lower edge of the symphysis (9.5 cm). When the tailbone leaves posteriorly during childbirth - 11.5 cm.
Transverse dimension - the distance between the inner surfaces of the ischial tuberosities (11 cm).

Sacral rhombus

When examining the pelvis, attention is paid to the sacral rhombus (Michaelis rhombus) - a platform on the back surface of the sacrum. Borders: upper corner - a depression between the spinous process of the V lumbar vertebra and the beginning of the middle sacral ridge; lateral angles - posterior superior iliac spine; lower - the top of the sacrum. Above and outside, the rhombus is bounded by the protrusions of the large dorsal muscles, below and outside - by the protrusions of the gluteal muscles.

Narrow pelvis

Until the 16th century, it was believed that the pelvic bones diverge during childbirth, and the fetus is born, resting its legs against the bottom of the uterus. In 1543, the anatomist Vesalius proved that the bones of the pelvis were rigidly connected, and doctors turned their attention to the problem of a narrow pelvis.

Pelvic anomalies are among the most common causes of abnormalities in labor. Despite the fact that in recent years, gross deformities of the pelvis and high degrees of its narrowing are rare, the problem of a narrow pelvis has not lost its relevance today - due to the acceleration and increase in the body weight of newborns.

The reasons

The reasons for the narrowing or deformation of the pelvis can be:

congenital pelvic anomalies,
malnutrition in childhood,
childhood illnesses: rickets, poliomyelitis, etc.
diseases or damage to the bones and joints of the pelvis: fractures, tumors, tuberculosis.
spinal deformities (kyphosis, scoliosis, coccyx deformity).
one of the factors in the formation of the transversely narrowed pelvis is acceleration, which leads to rapid growth of the body in length during puberty with a lag in the growth of transverse dimensions.

Views

Anatomically narrow a pelvis is considered in which at least one of the main dimensions (see below) is less than normal by 1.5-2 cm or more.

However, it is not the size of the pelvis that matters most, but the ratio of these sizes to the size of the fetal head. If the head of the fetus is small, then even with some narrowing of the pelvis, there may not be a discrepancy between it and the head of the baby being born, and childbirth takes place naturally without any complications. In such cases, an anatomically narrowed pelvis is functionally sufficient.

Labor complications can also occur with normal pelvic sizes - in cases where the fetal head is larger than the pelvic ring. In such cases, the movement of the head through the birth canal is suspended: the pelvis is practically narrow, functionally insufficient. Therefore, there is such a concept as clinically (or functionally) narrow pelvis... A clinically narrow pelvis is an indication for caesarean section during labor.

True anatomically narrow pelvis occurs in 5-7% of women. The diagnosis of a clinically narrow pelvis is established only in childbirth according to a set of signs that reveal the disparity between the pelvis and the head. This type of pathology occurs in 1-2% of all births.

How is the pelvis measured?

In obstetrics, the study of the pelvis is very important, since its structure and size are crucial for the course and outcome of labor. The presence of a normal pelvis is one of the main conditions for the correct course of labor.

Deviations in the structure of the pelvis, especially a decrease in its size, complicate the course of natural childbirth, and sometimes represent insurmountable obstacles for them. Therefore, when registering a pregnant woman at an antenatal clinic and when entering a maternity hospital, in addition to other examinations, it is imperative to measure the external dimensions of the pelvis. Knowing the shape and size of the pelvis, it is possible to predict the course of labor, possible complications, make a decision on the admissibility of spontaneous childbirth.

Examining the pelvis includes examining, feeling the bones and measuring the size of the pelvis.

In a standing position, examine the so-called lumbosacral rhombus, or Michaelis rhombus (Fig. 1). Normally, the vertical size of the rhombus is on average 11 cm, the transverse size is 10 cm. When the structure of the small pelvis is disturbed, the lumbosacral rhombus is not clearly expressed, its shape and size are changed.

After palpation of the pelvic bones, it is measured with a pelvic meter (see Fig. 2a and b).

The main dimensions of the pelvis:

Interosseous size. The distance between the superior anterior iliac spines (in Fig.2a) is normally 25-26
The distance between the most distant points of the iliac crests (in Fig.2a) is 28-29 cm, between the greater trochanters of the femurs (in Fig.2a) - 30-31 cm.
External conjugate - the distance between the supra-sacral fossa (upper corner of the Michaelis rhombus) and the upper edge of the pubic symphysis (Fig.2b) - 20-21 cm.

The first two sizes are measured with a woman lying on her back with her legs extended and together; the third dimension is measured with the legs shifted and slightly bent. The external conjugate is measured with the woman lying on her side with the lower leg bent at the hip and knee joints and the extended overlying leg.

Some pelvic sizes are determined during a vaginal examination.

When determining the size of the pelvis, it is necessary to take into account the thickness of its bones; it is judged by the value of the so-called Solovyov index - the circumference of the wrist joint. The average value of the index is 14 cm. If the Soloviev index is more than 14 cm, it can be assumed that the pelvic bones are massive and the size of the small pelvis is less than expected.

If it is necessary to obtain additional data on the size of the pelvis, in accordance with its size of the fetal head, deformation of bones and their joints, an X-ray examination of the pelvis is performed. But it is made only on strict indications. The size of the pelvis and its correspondence to the size of the head can also be judged by the results of ultrasound examination.

Influence of a narrow pelvis on the course of pregnancy and childbirth

The unfavorable effect of a narrowed pelvis on the course of pregnancy affects only in its last months. The head of the fetus does not descend into the small pelvis, the growing uterus rises and makes breathing much more difficult. Therefore, at the end of pregnancy, shortness of breath appears early, it is more pronounced than during pregnancy with a normal pelvis.

In addition, a narrow pelvis often leads to an incorrect position of the fetus - transverse or oblique. 25% of women in labor with a transverse or oblique position of the fetus usually have a more or less pronounced narrowing of the pelvis. Breech presentation of the fetus in women in labor with a narrowed pelvis occurs three times more often than in women in labor with a normal pelvis.

Management of pregnancy and childbirth with a narrow pelvis

Pregnant women with a narrow pelvis are at high risk of developing complications, and in the antenatal clinic should be on a special account. Timely detection of fetal anomalies and other complications is necessary. It is important to accurately determine the due date in order to prevent prolongation of pregnancy, which is especially unfavorable with a narrow pelvis. 1-2 weeks before giving birth, pregnant women with a narrow pelvis are recommended to be admitted to the pathology department to clarify the diagnosis and choose a rational method of delivery.

The course of labor with a narrow pelvis depends on the degree of narrowing of the pelvis. With a slight narrowing, medium and small size of the fetus, vaginal delivery... During childbirth, the doctor carefully monitors the function of the most important organs, the nature of the birth forces, the state of the fetus and the degree of conformity of the fetal head and the pelvis of the woman in labor and, if necessary, promptly resolves the issue of caesarean section.

Absolute the indication for a cesarean section is:

anatomically narrow pelvis

Narrow pelvis: features of pregnancy and childbirth

In the period of "interesting position", the size of the pelvis plays a very important role, because the specialist, based on them, chooses the tactics of delivery. If the pelvis is narrow, complications may occur during childbirth. In some cases, natural childbirth is not possible at all. The only way to give birth to a child (if a narrow pelvis is diagnosed during pregnancy) is by cesarean section. What kind of pelvis do doctors consider narrow and how do they define it? How will the pregnancy proceed with this diagnosis? Let's try to find answers to all these questions.

A bit of anatomy: the female pelvis

Everyone knows perfectly well such a part of the skeleton as the pelvis. It is conventionally subdivided into small and large. The uterus with the fetus is located in the large pelvis of a pregnant woman. The small pelvis is the birth canal. The baby is positioned head down to the opening of the small pelvis at 7-8 months of pregnancy. With the onset of labor, the fetus enters the pelvis.

The birth of a baby is a rather complicated process. The fruit undergoes various movements in order to adapt to the shape and size of the passage. Before giving birth, the baby's head is pressed to the breast. Then it turns to the left or right side when wedging into the pelvic entrance. After that, the head makes another turn. Thus, the child, passing through the small pelvis, changes the position of the head twice.

It should be noted that the head is the largest part of the child. Its passage through the birth canal is provided by:

contractile movements of the muscles of the uterus, which push the child forward;
the mobility of the fetal skull bones, which are not completely fused and are able to move slightly and thereby adapt to the size of the passage;
easy spreading of the pelvic bones.

The sizes of this part of the skeleton are different for each woman. For some, the pelvis may be normal, for some it may be narrow, and for some it may be wide. The narrow variety is a serious problem for pregnant women, since the process of having a baby in this case is not easy. Due to this anatomical feature, childbirth can be complicated. Women with a narrow pelvis most often do not give birth naturally, but through a cesarean section.

Anatomically narrow pelvis during pregnancy

An anatomically narrow pelvis is that part of the skeleton, all sizes of which (or one of them) differ from normal parameters by 1.5-2 cm. About 6.2% of pregnant women have this diagnosis. The peculiarity of the anatomical deviation is that the fetal head during childbirth may not pass through the pelvic ring. Natural childbirth is only possible if the baby is very small.

A narrow pelvis can be the result of exposure to certain reasons on the human body in childhood: frequent infectious diseases, malnutrition, lack of vitamins, hormonal disorders during puberty. The pelvis can be deformed due to damage to the bones in poliomyelitis, rickets, tuberculosis.

There is a classification of a narrow pelvis by shape. The most common varieties are:

flat pelvis (flat rachitic; simple flat; with a reduced straight plane size of the wide part of the pelvic cavity);
transversely narrowed pelvis;

Rarely encountered forms include:

oblique and obliquely displaced pelvis;
the pelvis, deformed due to fractures, tumors;
other forms.

Of great importance is the classification, compiled according to the degree of narrowing of the pelvis:

true conjugate is more than 9 cm, but less than 11 cm - 1 degree;
true conjugate is more than 7 cm, but less than 9 cm - 2 degree;
true conjugate is more than 5 cm, but less than 7 cm - 3 degree;
true conjugate less than 5 cm - 4 degree.

If a woman is diagnosed with 1 degree of narrowing, then natural childbirth is quite possible. They are allowed under certain conditions and with 2 degrees of narrowing of the pelvis. The rest of the varieties are always an indication for a planned cesarean section. Attempts to give birth on their own are excluded. More about caesarean section>

Clinically narrow pelvis during pregnancy

Experts also distinguish a clinically narrow pelvis. Its size is not less than the norm. It has absolutely normal physiological dimensions and shape. However, the pelvis is called narrow because the fetus is large. For this reason, a baby cannot be born naturally. Learn more about which fruit is considered large>

This type of narrow pelvis is caused not only by the large size of the fetus, but also by the incorrect insertion of the head of the child (the largest size). This also prevents the birth of the fetus.

Basically, this type of narrow pelvis is diagnosed during childbirth, but assumptions often arise in the last month of pregnancy. The doctor can predict the course of labor by analyzing the size of the fetus, which is revealed during the ultrasound, and the size of the woman's pelvis.

Complications that can occur during childbirth with the clinical appearance of a narrow pelvis are quite severe for both the mother and her unborn child. For example, the following consequences may be: oxygen starvation, respiratory failure, intrauterine fetal death.

How to identify a narrow pelvis in a pregnant woman?

A narrow pelvis in a pregnant woman should be diagnosed long before delivery. Women with severe narrowing 2 weeks before the expected date of birth are routinely hospitalized in the maternity ward to avoid possible complications.

How to identify a narrow pelvis? The parameters of this part of the skeleton are determined by the gynecologist at the first examination when registering with the antenatal clinic. He uses a special tool for this - pelvimeter... It looks like a compass and has a centimeter scale. Tazometer is designed to determine the external dimensions of the pelvis, the length of the fetus, the size of its head.

A narrow pelvis may be suspected prior to examination. As a rule, in women with such an anatomical feature, you can notice a male physique, short stature, small foot size, short toes. Orthopedic diseases (scoliosis, lameness, etc.) may appear.

How is a woman examined by a gynecologist? First of all, the specialist pays attention to the Michaelis rhombus located in the lumbosacral region. The pits above the coccyx and on the sides are its corners. The longitudinal size is normally about 11 cm, and the transverse one is 10 cm. The parameters of the rhombus, which are less than normal values, and its asymmetry indicate an irregular structure of the female pelvis.

A gynecologist, using a pelvimeter, determines the following parameters:

distance between the iliac crests. Normal value is more than 28 cm;
the distance between the anterior spines of the iliac bones (interosseous size). The norm of the parameter is more than 25 cm;
the distance between the greater trochanters of the femur. The normal value is 30 cm;
the distance between the upper edge of the pubic symphysis and the supra-sacral fossa (external conjugate). The norm of the parameter is more than 20 cm;
the distance between the pubic joint and the promontory of the sacrum. Obstetricians refer to this parameter as a true conjugate. Its value is determined by a vaginal examination. Normally, the gynecologist cannot reach the promontory of the sacral bone.

Some women have massive bones... Because of this, the pelvis may turn out to be narrow, even though all its parameters do not deviate from normal values. To assess the thickness of the bones, the Soloviev index is used - the circumference of the wrist is measured. Normally, it should be no more than 14 cm. The pelvis of a pregnant woman may be narrow if the wrist circumference is more than 14 cm.

An assessment of the size of a narrow pelvis can also be performed during an ultrasound examination (ultrasound). In very rare cases, radiopelviometry is performed. This study is undesirable for the fetus.

The doctor prescribes it only if there are strict indications, which include the following:

special obstetric examination of a pregnant woman

the age of a pregnant woman is from 30 years (provided that her first pregnancy);
high risk of perinatal pathology:
an unfavorable outcome of childbirth in the past (stillbirth, operative delivery through the vaginal birth canal, weakness of labor);
endocrine pathology (pituitary adenoma, hyperprolactinemia, hyperandrogenism);
history of miscarriage and infertility;
concomitant extragenital diseases;
suspicions of anatomical changes in the pelvis - postponed poliomyelitis and rickets, congenital dislocations of the hip joints, narrowing of the outer dimensions of the pelvis, a history of traumatic injuries;
suspicion of a disproportion between the fetal head and the woman's pelvis.

Radiopelviometry is performed using a low-dose digital radiographic unit.

All of the above relates to the diagnosis of an anatomically narrow pelvis. How does a doctor identify a clinical species? This diagnosis is made by a specialist during childbirth. The obstetrician may notice that the baby's head does not sink into the pelvic cavity, despite the fact that the contractions are strong, labor is good and the cervix is completely open. Doctors know specific signs that help to identify the lack of advancement of the fetal head. When diagnosing a clinical variety of a narrow pelvis, an emergency caesarean section is performed.

Pregnancy with a narrow pelvis

A narrow pelvis during pregnancy leads to the formation of abnormal fetal positions. Breech presentation is quite common. Oblique and transverse presentation of the fetus can also be diagnosed. More on Abnormal Fetal Presentations>

In the last trimester, a woman in a position may notice some features. For example, because of the narrow pelvis, the child's head is not pressed against the entrance to the small pelvis. This leads to shortness of breath in the woman. In primiparas with a narrow pelvis, the abdomen has a special shape - pointed. In multiparous women, the abdomen looks saggy, since the anterior abdominal wall is weak.

Childbirth with a narrow pelvis

A pregnant woman, when a narrow pelvis is detected at the stage of registration in an antenatal clinic, is observed in a special way, because complications are possible. Timely detection of the incorrect position of the child, prevention of post-pregnancy, hospitalization in the maternity ward at 37-38 weeks play an important role in the prevention of complications during childbirth.

A narrow pelvis during childbirth is a serious problem for obstetricians and gynecologists, because it is not so easy to decide whether a pregnant woman can give birth naturally.

In solving this issue, many factors are taken into account:

the size of the pelvis;
presence / absence of any pathology of pregnancy;
age of the fair sex;
the presence / absence of infertility in the past.

Doctors determine the tactics of childbirth, based on the degree of narrowing of the pelvis. For example, independent childbirth is possible if the fetus is small, its presentation is correct and the narrowing of the pelvis is insignificant.

With an anatomical variety of a narrow pelvis, premature rupture of amniotic fluid... The umbilical cord or fetal body parts (arms or legs) may fall out. Due to the early outpouring of amniotic fluid, the process of cervical dilatation slows down. Also, infections can enter the uterine cavity. They are the causes of endometritis (inflammation of the inner lining of the uterus), placentitis (inflammation of the placenta), and infection of the fetus. As a rule, contractions against this background are very painful. The first stage of labor is delayed in duration.

With a narrow pelvis, it is often observed birth force anomaly, contractile activity of the muscles of the uterus. During childbirth, rare and weak contractions are noted. The process of giving birth to a child is very delayed, and the woman in labor gets tired.

The second stage of labor is characterized by the development secondary weakness of labor... There are difficulties in advancing the fetal head. Against this background, intense pain, fatigue of the woman in labor are noted. Prolonged standing of the head in one plane leads to irritation of the receptors of the cervix, the lower segment of this organ.

The period of passage of the child through the birth canal is long. In the presence of pronounced obstacles to the birth of a baby, violent labor activity, excessive hyperextension of the bladder, rectum, and urethra may occur.

On the part of the expectant mother, a clinically narrow pelvis is a relative condition for a cesarean section, but on the part of the fetus, it is considered an absolute condition, since there is a threat of severe consequences and death of the child.

Quite often, pregnant women who have been diagnosed with a clinically narrow pelvis experience untimely rupture of amniotic fluid. The child's head is in the same plane for a long time. This leads to weakness of labor, the formation of intestinal and genitourinary fistulas, trauma to the birth canal. Craniocerebral trauma to the fetus is not uncommon. The threat of complications leads to the completion of labor by surgery.

Caesarean section with a narrow pelvis: indications

Indications for surgery with a narrow pelvis can be divided into 2 groups: absolute and relative.

Absolute indications include:

narrow pelvis 3 and 4 degrees;
pronounced deformities of the pelvis;
damage to the joints and pelvic bones in previous births;
bone tumors of the small pelvis.

In all of the above cases, natural childbirth is impossible. A child can be born exclusively through a cesarean section. It is carried out on a planned basis until the onset of labor or with the onset of the first contractions.

Relative indications for caesarean section include:

narrow pelvis of 1 degree in combination with one or more additional factors:
large fruit;

The bony pelvis consists of a large and small pelvis. The border between them: behind - the sacral promontory; from the sides - nameless lines, in front - the upper part of the pubic symphysis.

The bony base of the pelvis is made up of two pelvic bones: the sacrum and the coccyx.

The female pelvis is different from the male pelvis.

A large pelvis is not important in obstetric practice, but it is available for measurement. By its size, one can judge the shape and size of the small pelvis. An obstetric pelvis meter is used to measure the large pelvis.

The main the size of the female pelvis:

In obstetric practice, a fundamental role is played by the small pelvis, which consists of 4 planes:

The plane of the entrance to the pelvis.
The plane of the wide part of the small pelvis.
The plane of the narrow part of the pelvic cavity.
Exit plane from the pelvis.

The plane of the entrance to the small pelvis

Borders: behind - the sacral promontory, in front - the upper edge of the pubic symphysis, on the sides - nameless lines.

The straight dimension is the distance from the sacral promontory to the upper edge of the false articulation of 11 cm. The main dimension in obstetrics is coniugata vera.

Transverse size 13 cm - the distance between the most distant points of the nameless lines.

Oblique dimensions are the distance from the sacroiliac joint on the left to the false protrusion on the right and vice versa - 12 cm.

The plane of the wide part of the small pelvis

Borders: in front - the middle of the false articulation, behind - the junction of the 2nd and 3rd sacral vertebrae, on the sides - the middle of the acetabulum.

It has 2 sizes: straight and transverse, which are equal to each other - 12.5 cm.

The straight size is the distance between the gray pubic articulation and the junction of the 2nd and 3rd sacral vertebrae.

The transverse dimension is the distance between the midpoints of the acetabulum.

The plane of the narrow part of the pelvic cavity

Borders: in front - the lower edge of the pubic symphysis, behind - the sacrococcygeal joint, on the sides - the sciatic spines.

The straight size is the distance between the lower edge of the pubic joint and the sacrococcygeal joint - 11 cm.

The transverse dimension is the distance between the ischial spines - 10.5 cm.

Exit plane from the pelvis

Borders: in front - the lower edge of the pubic articulation, behind - the apex of the coccyx, on the sides - the inner surface of the ischial tubercles.

The straight dimension is the distance between the lower edge of the symphysis and the apex of the coccyx. During childbirth, the fetal head deflects the tailbone by 1.5-2 cm, increasing the size to 11.5 cm.

Transverse dimension - the distance between the ischial tubercles is 11 cm.

The angle of inclination of the pelvis is the angle formed between the horizontal plane and the plane of the entrance to the small pelvis, and is 55-60 degrees.

The wired axis of the pelvis is a line connecting the vertices of all straight dimensions of the 4 planes. It is not in the shape of a straight line, but concave and open in front. This is the line along which the fetus passes, being born through the birth canal.

Pelvic conjugates

External conjugate - 20 cm. Measured with a pelvometer during external obstetric examination.

Diagonal conjugate - 13 cm. Measured by hand during internal obstetric examination. This is the distance from the lower edge of the symphysis (inner surface) to the sacral promontory.

The true conjugate is 11 cm. This is the distance from the upper edge of the symphysis to the sacral promontory. Measurement is not available. Calculated by the magnitude of the outer and diagonal conjugate.

External conjugate:

9 is a constant number.

20 - external conjugate.

Diagonal conjugate:

1.5-2 cm is the Soloviev index.

The thickness of the bone along the circumference of the wrist joint is determined. If it is 14-16 cm, then 1.5 cm is subtracted.

If 17-18 cm - 2 cm is subtracted.

Rhombus Michaelis - education, which is located on the back, has a diamond shape.

Has dimensions: vertical - 11 cm and horizontal - 9 cm. In total (20 cm) giving the value of the external conjugates. Normally, the vertical dimension corresponds to the true conjugate value. By the shape of the rhombus and its size, the condition of the small pelvis is judged.

Every woman wants to know the joy of motherhood. This is a natural impulse associated with the very essence of human nature. However, many find themselves not ready for the fact that they will have to regularly visit a doctor and endure some not particularly pleasant manipulations. But in order for the pregnancy to go smoothly and calmly, it is better to follow the instructions of the specialists than to rely on luck.

Preparation for the examination

Before you come to the antenatal clinic to register for pregnancy or just for a routine examination, the fair sex needs to put herself in order. No special effort is required, but it is still recommended to take a shower. In no case should you douche or something like that, because the general picture of the disease (if any) will be blurred and the doctor will not find anything. Fresh clean linen and a sanitary napkin (if necessary) will not be superfluous.

General and special history

Like any other doctor, the obstetrician-gynecologist has a standard form for reviewing the patient's history. It includes passport data, complaints, records of the place of residence and work, the presence of hereditary diseases and previous infections is indicated.

A special anamnesis is focused on ensuring that the doctor understands the essence of the problem with which the woman applies. It includes questions about menstruation, sexuality, pregnancy and abortion. In addition, a summary of the patient's spouse or partner, as well as his and her fertility, is required.

Then the examination for the current pregnancy is started. The gestational age is established, the size of the pelvis and the position of the child in the uterus are determined.

Determination of the gestational age

There are several ways to calculate gestational age and due date. The first one is the calendar one. It is the simplest one. You need to remember the number of the first day of the last menstruation and add 280 +/- 7 days or 10 lunar months to it. So you can find out the approximate day of the happy event. If a woman manages to remember the date of conception, then you need to add all the same 40 weeks again and get an answer to an exciting question.

Another method is based on ultrasound examination. The diagnostician, by indirect signs, can determine the gestational age of the fetus and state the approximate date of birth. With an obstetric study, the gestational age is also calculated by the height of the uterine fundus. From 12 to 38 weeks, the height of the uterus in centimeters corresponds to the week of pregnancy. You can also focus on the first movement of the fetus. In primiparas, it is felt from the eighteenth week, and in multiparous - from the sixteenth.

The size of the large pelvis

For a doctor, knowledge about the size of a woman's pelvis is important, and the data is important both during fetal development and during childbirth. The sizes include the external conjugate and three distances corresponding to the protruding parts of the pelvic and femur bones.

1. Distantia spinarum is the interval between the most elevated points of the spines of the iliac bones. It is equal to about twenty-six centimeters.

2. Distantia cristarum - the space between the ridges and it is approximately twenty-eight centimeters.

3. Distantia trochanterica - the distance between the large trochanters, located on the femurs, is 31-32 centimeters, respectively.

The outer conjugate has a slightly different size. If the three previous ones were located in then this one is in the sagittal. The outer conjugate is the distance between the protruding process of the fifth lumbar vertebra and the superior spine. Some preparations are needed to measure it. The determination of the external conjugate begins with the patient being placed on her side. The woman brings the leg, which lies on the couch, to the stomach, and stretches the overlying one. The branches of the pelvis are diluted and set over the pubic joint and the supra-sacral fossa so that they are practically parallel. This is an external conjugate. The measurement depends on the woman's constitution and the thickness of her bones. The thicker they are, the greater the calculation error. The outer conjugate is about twenty centimeters in size. Its calculation is necessary to determine the average difference between them corresponds to 9 centimeters. For example, if the outer conjugate is twenty centimeters, then the true one will be 11 cm.

The size of the small pelvis

There is such a thing as a narrowed pelvis. It can be narrowed clinically or anatomically. In order to find out the anatomical parameters of the bone ring, measurements of the small pelvis are made.

The diagonal conjugate is the length from the lower edge to the most prominent part of the sacrum. It is equal to 13 centimeters. It can only be determined when calculating the true conjugate from the outer and diagonal is that 9 cm is subtracted from the outer, and 2 cm from the diagonal. As a rule, the true conjugate is at least 11 centimeters. It is in order to calculate this parameter that an external conjugate is needed. Its rate may vary, depending on the thickness of the woman's bones, so doctors are reinsured and conduct an internal study. Bone thickness does not affect the diagonal conjugate.

The straight size of the exit from the pelvis is defined as the gap between the lower ridge of the pubic joint and the tip of the coccyx. The measurement is carried out with a pelvis meter, and is 11 cm.

The transverse size of the exit of the pelvis is the gap between the ischial tubercles. It can be carried out with both a pelvimeter and a centimeter tape. Normally, it is nine centimeters, but if we add the thickness of the soft tissues, we get 11 cm.

The lateral dimensions of the pelvis are necessary to determine the symmetry of the location of the bones. They must be at least 14 cm, otherwise childbirth will be difficult or impossible.

Michaelis rhombus

The external conjugate has a certain relation to the Michaelis rhombus, since it also shows the size of the pelvis. This is the platform formed by the posterior surface of the sacrum. Its boundaries:
- the fifth lumbar vertebra;
- Paired posterior superior spine of the iliac bones;
- the top of the sacrum.

The size is normally 11 by 11 centimeters. The outer conjugate has an upper point in common with the rhombus.

Manual receptions in obstetrics

After the twentieth week, the obstetrician-gynecologist can feel the head, back and limbs of the baby in the womb. For this, the techniques of external obstetric research are used.

First method: the doctor determines the height of the uterine fundus and the part of the fetal body that is adjacent to it. To do this, the doctor puts his palms on the top of the abdomen and feels it.

The second technique determines the position and appearance of the child. To do this, the obstetrician slowly lowers his hands from the top of the abdomen, spreading them to the sides. Pressing on the lateral surfaces of the uterus, fingers and palm, the doctor feels the back or small parts of the fetus's body, thus determining the articulation of the child.

The third technique is necessary to determine the underlying part, that is, that part of the body that is located above the pubic articulation. He can also determine the mobility of the head.

The fourth method complements the third. It allows you not only to identify the underlying part, but also to understand how it is located in relation to the entrance to the small pelvis. To do this, the doctor stands with his back to the patient and positions his hands in such a way that the fingers converge over the pubic symphysis.

View and in the uterus

Position is the position of the baby's back to the side of the uterus. Distinguish between the first position when the back is on the left side, and the second - when the child is turned with his back to the right. The first position is more common than the second.

Position type - the ratio of the back to the anterior or posterior wall of the uterus. Accordingly, if the child is leaning against the front wall of the uterus, they talk about the front position, and vice versa.

With an external obstetric examination, the Leopold-Levitsky techniques give the doctor the opportunity to determine the location of the fetus and predict the course of labor.

Internal research

Internal obstetric examination can be performed with two or four fingers, or with the entire hand. By touch, the doctor can determine the degree of cervical dilatation, identify the presenting part, the integrity of the fetal bladder, the state of the birth canal. In addition, this method records the dynamics of the child's progress through the birth canal.

However, this is a rather serious intervention, and the procedure must be performed strictly according to the regulations: upon admission to the hospital, and then no more than once every two hours. The less often the better.

The study begins with an examination of the external genitalia and perineum. Then fingers are inserted into the vagina and its length, width, wall elasticity, the presence of scars, adhesions or strictures that can interfere with the normal course of labor are determined. After that, they move to the cervix. It is examined for maturity, shape, size and consistency, shortening and softening. If a woman enters in childbirth, then the cervical opening is measured in the patency of the fingers. In addition, the doctor tries to grope for the presenting part and determine the position of the head in order to prepare for possible complications.

Determining the position of the baby's head

There are three degrees of extension of the head when it passes through the birth canal.

The first degree (anterior-head insertion) means that the head will pass through the pelvis in its straight size. It is equal to 12 cm. This means that the cervix and vagina should be stretched by this amount.

The second degree (frontal insertion) corresponds to a large oblique size (13-13.5 cm). This will be the largest part that must pass through the birth canal.

The third degree (face insertion) tells the obstetrician that the child is moving face forward through the small pelvis, which means that the largest head size will correspond to 9.5 cm.

Pelvis shape
Normal
Transversely
General uniform
Infantile
Simple flat
Flat rachitic
Generally narrowed flat

During vaginal examination, the diagonal conjugate is measured (12.5-13 cm). Obstetric conjugate - c. vera (subtract 2 cm from the size of the diagonal conjugate).

The true conjugate is calculated:

on a diagonal line;

by external conjugate;

by the vertical size of the Michaelis rhombus;

using roentgenopelviometry;

according to ultrasound data.

The capacity of the small pelvis depends on the thickness of its bones, which is indirectly determined by measuring the circumference of the wrist joint with the calculation of the Solovyov index (13.5-15.5 cm).

Michaelis rhombus (normal - 11 x 10 cm).

The direct size of the exit of the small pelvis (9.5 cm).

The transverse size of the exit of the small pelvis (11 cm).

The pubic angle (90 0 -100 0).

External oblique dimensions of the pelvis.

Lateral conjugate (the distance between the anterior and posterior superior spines of the ilium on one side) is 15 cm.

Distance from the anterior-superior spine on one side to the posterior-superior spine on the other side (21-22 cm).

Distance from the middle of the upper edge of the symphysis to the posterior-superior spines on the right and left (17.5 cm); the difference in size indicates the asymmetry of the pelvis.

Distance from the supra-sacral fossa to the anterior-superior spines on both sides.

The circumference of the pelvis at the level of the iliac crests (85 cm); the same at the level of the large skewers (90 - 95 cm).

The height of the standing of the fundus of the uterus; abdominal circumference.

Fetal head diameter (12 cm).

The pubo-sacral size (the distance from the middle of the symphysis to the junction of the 2nd and 3rd sacral vertebrae is the point located 1 cm below the intersection of the diagonals of the Michaelis rhombus - 22 cm); a decrease in this size by 2-3 cm is accompanied by a decrease in the direct size of the wide part of the pelvic cavity.

Radiopelviometry allows you to determine all diameters of the small pelvis, the shape, inclination of the pelvic walls, the shape of the pubic arch, the degree of curvature and inclination of the sacrum. It is recommended to produce at 38-40 weeks. pregnancy or before the onset of labor.

Ultrasound examination - ultrasound, is used to diagnose anatomically narrow pelvis and makes it possible to obtain the value of the true conjugate and biparietal size of the fetal head, their ratio.

The course of pregnancy and childbirth with a narrow pelvis

A narrow pelvis as such does not lead to a change in the course of pregnancy.

The unfavorable effect of a narrowed pelvis on the course of pregnancy affects its last months and at the beginning of childbirth.

Features that an obstetrician should know about:

In primiparous, due to the discrepancy between the pelvis and the head, the latter does not enter the pelvis and remains mobile above the entrance throughout pregnancy and at the beginning of labor. The height of the uterine fundus on the eve of childbirth remains the same.

In primiparous women with a narrow pelvis by the end of pregnancy, the abdomen has a pointed shape, and in multiparous women it is saggy.

Anomalies of the pelvic bone are common causes of abnormal fetal position - oblique, transverse and pelvic presentation of the fetus, as well as unfavorable insertion of the head - extensor.

One of the frequent and serious complications of pregnancy with a narrow pelvis is premature (prenatal) effusion. This is due to the absence of a belt of contact - the head stands high, it does not touch the pelvic ring, so the waters are not divided into anterior and posterior - the entire mass at the beginning of labor is poured out under increasing uterine pressure.

When the amniotic fluid and the movable head of the fetus are poured out, there is a great danger of the umbilical cord and small parts of the fetus falling out. The prolapse of the umbilical cord leads to the development of acute fetal hypoxia and its death if the head presses it against the pelvic wall. In these cases, only an emergency caesarean section can save the child (intrapartum mortality among newborns in these cases is 60-70%).

With a narrow pelvis, childbirth is often complicated by the weakness of labor. Firstly, women with a narrow pelvis have hormonal insufficiency, sexual infantilism, and secondly, childbirth is protracted, which leads to fatigue of the woman in labor, depletion of energy resources and the development of secondary weakness of labor.

Mother's injury. Prolonged compression of the bladder and rectum by the head of the fetus can lead to the formation of urogenital and intestinal fistulas (on the 6-7th day). Compression of the cervix can lead to edema, necrosis, and deep tears.

The lack of forward movement of the fetus with continued intensive labor, leads to a gradual thinning of the lower segment and the emergence of a threatening rupture of the uterus.

With a prolonged course of labor with a long anhydrous interval significantly increases the risk of developing endometritis, chorioamnionitis, ascending infection of the fetus.

Complications from the fetus. The fetal head configures slowly, lingers for a long time in various planes of the small pelvis, which causes cerebrovascular accident, edema, an increase in head volume, the formation of cephalohematomas, subdural and subarachnoid hemorrhages. With the further development of the child in these areas, a cicatricial adhesive process is formed, leading to the occurrence of deviations in the neuropsychic sphere and physical development up to the development of hydrocephalus, hyperkinesis, epilepsy and dementia. Moreover, with deep, irreversible dysfunctions of the brain, infantile cerebral palsy can form.

Distantia spinarum - the distance between the anterior-superior spines of the iliac bones is 25-26 cm.
Distantia cristarum - the distance between the distant points of the iliac crests is 28-29 cm.
Distantia trochanterica - the distance between the large trochanters of the femurs, normally 30-31 cm.
Conjugata externa (external conjugate, straight size of the pelvis) - the distance from the middle of the upper-outer edge of the symphysis to the supracranial fossa, located between the spinous process of the V lumbar vertebra and the beginning of the middle sacral ridge (coincides with the upper angle of the Michaelis rhombus), is 20-21 cm.

The size of the small pelvis

Conjugata vera (true conjugate, direct size of the entrance to the small pelvis) - the distance from the inner surface of the symphysis to the promontory of the sacrum; to determine the true conjugate, 9 cm is subtracted from the dimensions of the external conjugate.Normally, the true conjugate is 11 cm.
Anatomical conjugate - the distance from the cape to the middle of the upper inner edge of the symphysis (11.5 cm).
Transverse dimension - the distance between the most distant points of the arched lines (13-13.5 cm).
The oblique dimensions are 12-12.5 cm. The right oblique dimension is the distance from the right sacroiliac junction to the left ilio-pubic eminence (eminentia iliopubica). Left oblique dimension - the distance from the left sacroiliac junction to the right ilio-pubic eminence (eminentia iliopubica).

Direct size - the distance from the junction of the II and III sacral vertebrae to the middle of the inner surface of the symphysis, is 12.5 cm.
Transverse dimension is the distance between the midpoints of the acetabulum (12.5 cm).

Straight size - the distance from the sacrococcygeal junction to the lower edge of the symphysis (11-11.5 cm).
Transverse dimension - the distance between the spines of the ischial bones (10.5 cm).

4. The plane of the exit of the pelvis is limited by the lower edge of the symphysis (front), ischial tubercles (from the sides) and the apex of the coccyx (back).

Straight size - from the top of the coccyx to the lower edge of the symphysis (9.5 cm). When the tailbone leaves posteriorly during childbirth - 11.5 cm.
Transverse dimension - the distance between the inner surfaces of the ischial tuberosities (11 cm).